Why Does My Heart Beat Faster Sometimes?

Chloe Effron // iStock
Chloe Effron // iStock

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

You probably know that exercise—running, jumping, swimming, dancing—will make your heart beat faster. But did you know that your heart rate also speeds up when you feel scared, nervous, angry, or excited? Your movements and your feelings can give your heart a little workout. It’s your body’s way of making sure you are prepared for anything. 

Your heart is a muscle that pumps blood to the lungs to get oxygen, and then to the rest of the body. That’s really important, because the cells in your body need oxygen to survive! When you exercise, your muscles need even more oxygen because they are working harder. The faster your heart beats, the faster it can get more blood and oxygen to your muscles. And when you feel scared, angry, or excited, your brain also tells your heart to be faster. 

When your brain senses danger—like a bully at school, a fire, or an angry dog—it has to decide whether to stay and fight the danger, or run away from it. This reaction is called “fight or flight.” Fear causes the brain to release a chemical called adrenaline (uh-DREN-uh-lin), which speeds up your breathing and heart rate. The extra oxygen gives you the strength and brain power to fight back—or run away as fast as you can. This can happen even when you’re not in a life-threatening situation, but just feeling nervous or excited: watching a scary movie, performing on stage, having an argument with a friend, or riding a roller coaster.

Play this quick game from the BBC's Bitesize to see how activities change how fast the heart beats.

The Great Tryptophan Lie: Eating Turkey Does Not Make You Tired

bhofack2/iStock via Getty Images
bhofack2/iStock via Getty Images

While you’re battling your cousins for the best napping spot after Thanksgiving dinner, feel free to use this as a diversion tactic: It’s a myth that eating turkey makes you tired.

It’s true that turkey contains L-Tryptophan, an amino acid involved in sleep. Your body uses it to produce a B vitamin called niacin, which generates the neurotransmitter serotonin, which yields the hormone melatonin, which helps regulate your sleeping patterns. However, plenty of other common foods contain comparable levels of tryptophan, including other poultry, meat, cheese, yogurt, fish, and eggs.

Furthermore, in order for tryptophan to produce serotonin in your brain, it first has to make it across the blood-brain barrier, which many other amino acids are also trying to do. To give tryptophan a leg up in the competition, it needs the help of carbohydrates. Registered dietitian Elizabeth Somer tells WebMD that the best way to boost serotonin is to eat a small, all-carbohydrate snack a little while after you’ve eaten something that contains tryptophan, and the carbs will help ferry the tryptophan from your bloodstream to your brain.

But Thanksgiving isn’t exactly about eating small, well-timed snacks. It’s more about heaps of potatoes, mountains of stuffing, and generous globs of gravy—and that, along with alcohol, is more likely the reason you collapse into a spectacular food coma after your meal. Overeating (especially of foods high in fat) means your body has to work extra hard to digest everything. To get the job done, it redirects blood to the digestive system, leaving little energy for anything else. And since alcohol is a central nervous system depressant, it also slows down your brain and other organs.

In short, you can still hold turkey responsible for your Thanksgiving exhaustion, but you should make sure it knows it can share the blame with the homestyle mac and cheese, spiked apple cider, and second piece of pumpkin pie.

[h/t WebMD]

Sorry, Plant Parents: Study Shows Houseplants Don’t Improve Air Quality

sagarmanis/iStock via Getty Images
sagarmanis/iStock via Getty Images

Sometimes accepted wisdom needs a more thorough vetting process. Case in point: If you’ve ever heard that owning plants can improve indoor air quality in your home or office and act as a kind of organic air purifier or cleaner, you may be disappointed to learn that there’s not a whole lot of science to back that theory up. In fact, plants will do virtually nothing for you in that respect.

This botanic bummer comes from Drexel University researchers, who just published a study in the Journal of Exposure Science and Environmental Epidemiology. Examining 30 years of previous findings, Michael Waring, an associate professor of architectural and environmental engineering, found only scant evidence that plants do anything to filter contaminants from indoor air.

Many of these studies were limited, the study says, by unrealistic conditions. Plants would often be placed in a sealed chamber, with a single volatile organic compound (VOC) introduced to contaminate the air inside. While the VOCs decreased over a period of hours or days, Waring found that the studies placed little emphasis on measuring the clean air delivery rate (CADR), or how effectively an air purifier can “clean” the space. When Waring converted the studies' results to CADR, the plants's ability to filter contaminants was much weaker than simply introducing fresh air to disperse VOCs. (Additionally, no one is likely to live in a sealed chamber.)

The notion of plants as natural air filters likely stemmed from a NASA experiment in 1989 which argued that plants could remove certain compounds from the air. As with the other studies, it took place in a sealed environment, which made the results difficult to translate to a real-world environment.

Plants can clean air, but their efficiency is so minimal that Waring believes it would take between 10 and 1000 of them per square meter of floor space to have the same effect as simply opening a window or turning on the HVAC system to create an air exchange. Enjoy all the plants you like for their beauty, but it’s probably unrealistic to expect them to help you breathe any easier.

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